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  1. #1

    RAID 1 vs. RAID 5

    I am looking for opinions on RAID 1 vs. RAID 5. Which is better, RAID 5 seems like a more effecient use of disk space but does performance suffer?

  2. #2
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    Do a search, for speed go with Raid1. The only time I'd use Raid5 is in a very large storage array where maxamizing space was the goal and speed was second.

    A raid solution is only better when it fits your specific needs.
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  3. #3
    I am definately looking redundancy which is why I want a system with RAID, I guess i just need to decide which is more important to me at this point. This will be a DB server, so speed is definately a concern. Maybe RAID 5 isnt the best option.

  4. #4
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    For a database server I would go RAID1. If you do a search there is a nifty link that explains the differences and has the pros/cons of each.
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  5. #5
    RAID5 is the best option if you are making the RAID array for webserver... which can save your space and can provide redundancy.
    Choose the right option ... The world is open for You..

  6. #6
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    Originally posted by linuxentric
    RAID5 is the best option if you are making the RAID array for webserver... which can save your space and can provide redundancy.
    I would agree only if you enjoy IO Wait or need to maxamize space.
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  7. #7
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    Whichever you go with, make sure you get a card that's fully hardware RAID like a 3ware Escalade. Most cheap RAID cards are simply ATA/SATA cards that have additional BIOS code to let the host OS boot from the volume; some cheaper RAID 5 cards contain hardware XOR units but are still handled mostly through software drivers. A card with proper RAID 1 support will allow you to interleave reads, leading to very good read performance while only minimally compromising write speeds.

    Make sure you also understand that RAID is not a substitute for regular backups, merely a complement to them.

  8. #8
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    Raid 5 is more cost effective. Raid 1 is preferred by many.

    Raid 51 (or 15?) is the best of both worlds. (ie. two raid 5's with a Raid 1 connecting them.

    We've always preferred Raid 1, but if you decide to run Raid 5, you might also want to run a hot standby drive. If by chance you had a second drive go bad before you could replace the first, your server would still be functional.

  9. #9
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    Raid51? Is this like Area 51, heard of but no-one's ever seen it? :-)

    Raid 01 is the one to go for - ie striped disks, mirrored for redundancy. Raid0 is where you stripe data across several disks whch improves performance (ie. you have several disks that look like one big disk), however raid0 does not provide redundancy at all - if 1 disk fails, all the data is gone. So you mirror them to get the best of both worlds - speed and redundancy.

    There is no reason in the world to mix raid configurations otherwise, so raid 51 would give you nothing except slow performance.


    (and yes, off-site backups are essential, even if you have 2 raid-1 disks, they mean nothing if a power surge fries both their controllers)

  10. #10
    RAID 5 rebuilds take forever

  11. #11
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    Originally posted by gbjbaanb
    Raid51? Is this like Area 51, heard of but no-one's ever seen it? :-)

    Raid 01 is the one to go for - ie striped disks, mirrored for redundancy. Raid0 is where you stripe data across several disks whch improves performance (ie. you have several disks that look like one big disk), however raid0 does not provide redundancy at all - if 1 disk fails, all the data is gone. So you mirror them to get the best of both worlds - speed and redundancy.

    There is no reason in the world to mix raid configurations otherwise, so raid 51 would give you nothing except slow performance.


    (and yes, off-site backups are essential, even if you have 2 raid-1 disks, they mean nothing if a power surge fries both their controllers)
    Raid 51 does exist and is quite a good solution if it fits your needs. If you are in a mission-critical situation and need extreme redundancy, raid 51 takes the cake. It's the only solution that uses both parity and mirroring. It is the most fault-tolerant type of raid system you can get into.

    See: http://www.pcguide.com/ref/hdd/perf/...Level15-c.html for more information.
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  12. #12
    Look, for a web server, RAID 5 is absolutely wonderful.

    For a Virtuozzo node, RAID 5 is suicide.
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  13. #13
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    also if your planning to go with IDE raid (personally... i wouldn't) make sure you put only one drive per cable..... putting a source & mirror drive one one cable will cripple performance.

    I find raid1 nice... its what i use for database & file servers.

    rebuilding isn't too slow... and its relitivelly easy to rebuild a raid1 array.

    i've never suffered two drives die at once..... all my servers are on surge protection & ups systems.... but i still make sure i take backups of important data (onto a server at a different location).

  14. #14
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    Originally posted by gbjbaanb

    There is no reason in the world to mix raid configurations otherwise, so raid 51 would give you nothing except slow performance.
    Slow performance?

  15. #15
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    as justadollarhostin's link said: "RAID 10 provides most of the benefits with better performance and lower cost".

    If you are even thinking about raid 5+1, then you either need: a) multiple servers in different datacentres, or b) your head looking at. There's a limit to the amount of disk-failure paranoia that can't be satisfied by raid 1, or the performance extremism that can't be satisfied by raid 0. :-)

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